DESCRIPTION: This project is designed to satisfy the need for a new generation of accurate and non-invasive blood monitoring devices with multi-analyte, multi-signal capability. The specific goal to be pursued in Phase I is to demonstrate the feasibility of a breadboard device for the non-invasive and simultaneous detection of oxy-hemoglobin, deoxy- or reduced hemoglobin, carboxy-hemoglobin, and met-hemoglobin in arterial blood. The breadboard will be based on the differential absorption and multiple scattering analysis technologies. Analysis of scattered radiation will be investigated using the one-dimensional diffusion equation and the two-stream radiative transfer equation. The innovative idea of applying the combined technologies to the feasibility study of an optical blood sensor will lead to the potential simultaneous and non- invasive monitoring of human blood. Advanced algorithms for inverting, rather than fitting, the physical parameters of blood from the measurements of light transmitted through tissue will lead to more accurate blood diagnosis. The long-term objective is to develop a real- time non-invasive replacement of co-oximeters for monitoring blood hemoglobin moieties, blood gases, and drug/alcohol levels in blood for health and law-enforcement related applications.